JPS6119854B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic adjustment device for devices such as brakes, clutches, etc. that include friction members that require periodic adjustment.

The invention particularly provides for automatically increasing the distance between two relatively movable parts of a device including a friction member, forming an extensible member, one of which is attached to a first part of the device. a pair of relatively rotatable elements connected to the same part so as not to rotate with respect to each other; an actuating device for rotating the extensible member in a direction corresponding to its elongation; and a one-way coupling device between a second portion of the device and the other element to prevent rotation of the same in the opposite direction. The present invention relates to an automatic adjustment device of the type including.

This type of automatic adjustment device is suitable for disc brakes,
When a device such as a drum brake or clutch is activated, the distance separating the two parts is automatically increased to absorb wear on the friction member that performs brake activation or torque transmission.

In disc brakes or drum brakes, the two parts of the brake that require this adjustment are the piston and the cylinder that houses the piston, the two pistons facing each other with their backs facing each other, or the piston and the brake being adjusted mechanically. It is an actuating member that is activated. Additionally, an actuation gap is typically provided within the self-adjusting device to compensate for deformation of the brake under stress and to prevent over-adjustment that can generate residual brake torque when the brake is not actuated. To prevent. It is desirable that the working clearance in the self-adjusting device be limited to a small value; however, if the working clearance is small, there is a risk of over-adjustment. In vehicles equipped with a brake force distribution valve that limits the pressure supplied to the rear brakes, the pressure supplied to the front brakes is considerably higher than the pressure supplied to the rear brakes.
Since the stress acting on the brakes is different between the front and rear brakes, even a small working gap for the rear brakes can eliminate the risk of overadjustment, but the working gap of the front brakes is larger than that of the rear brakes. I will have to.

The present invention has been proposed in view of the above, with the aim of making it possible to limit the working clearance in automatic adjustment devices to small values, while eliminating the risk of over-adjustment commonly caused by small working clearances. There is.

To achieve this objective, the invention provides that the actuating device comprises at least one abutment member connected to the second part of the device and cooperating with the other element via a thrust bearing including a retainer. The retainer and the abutting member include an adjustment limiting device in which the elements cooperate with each other via a reversely rotatable screw, and limit rotation of the other element to within a predetermined angle each time the device is actuated. and a circumferential connection having a play therebetween, the play allowed by the connection defining the predetermined angle. The above type of automatic adjustment device is provided.

According to the above configuration, when the other element is rotated relative to one element by the abutting member of the actuating device and the thrust bearing during operation, the holder provided between the abutting member and the thrust bearing retainer The circumferential connection with play limits the rotation of the other element to an angle corresponding to the play, so that even if the working gap in the automatic adjustment device is set to a small value, over-adjustment is prevented. can be reliably prevented.

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, the disc brake slides via mounting pins 12 (only one shown) onto a fixed support 14 connected to a fixed element such as a short axle of the vehicle (not shown). It includes a movably mounted caliper 10. The caliper 10 straddles a rotating disk 16 connected to a rotating part of the vehicle, and slidably supports and anchors two friction members 18 and 20. The friction members each have a friction surface 2 of the disk 16.
2 and 24. Overall code 2
A fluid drive device 6 and a mechanical drive device 28 are incorporated into the caliper 10 and are connected to the friction member 2.
0 is directly engaged with the friction surface 24 of the disk 16, and the friction member 18 is brought into contact with the friction surface 24 of the disk 16 by sliding the caliper 10 along the mounting pin 12.
2 to operate the brake.

Fluid drive 26 includes a piston 30 that is slidably received within a blind cylinder 32 and defines a variable volume chamber 34 that is connected to a source of fluid pressure, such as a vehicle master cylinder (not shown).

Mechanical drive 28 includes a rotation shaft 36 connected to an actuation lever (not shown). Rotation of shaft 36 controls linear movement of actuating member 38 via force transmitting elements 40 housed in recesses 42 and 44 formed in shaft 36 and actuating member 38, respectively. The actuating member 38 is in the form of a push rod and is prevented from rotating by the engagement of the force transmitting element 40 with the recess 44 and extends fluid-tightly through the bottom 46 of the cylinder 32 to provide an automatic actuator generally designated 48. It engages the piston 30 via an adjustment device. A spring 50, which in this embodiment consists of a stack of dishwashers, normally urges the actuating member 38 toward the rest position. Furthermore, a wire spring 5 in contact with the bottom 46 of the cylinder 32
2 pushes the shaft 36 towards the rest position while preventing the force transmitting element 40 from escaping.

The automatic adjustment device 48 is configured to automatically increase the distance between the two parts of the brake, the piston 30 and the actuating member 38, upon activation of the fluid drive device 26. The regulating device 48 has two elements 5
4 and 56, relative rotation of the elements in one direction causes the extensible member to elongate. Element 54 is a nut and element 56 is a threaded rod integral with actuating member 38. elements 54 and 56
cooperate with each other via counter-rotatable screws 58. Self-adjusting device 48 also includes an actuating device, generally designated 60, coupled to piston 30. The actuating device 60 includes an abutment member consisting of a washer 62 that exerts a thrust force on the nut 54 via a thrust ball bearing 64 when the fluid drive device 26 is actuated. The abutment washer 62 is disposed within the large diameter portion of the stepped hole 66 of the piston 30, and is secured to the stepped hole 66 by a retaining ring 68.
It is held in contact with the shoulder of the Automatic adjustment device 48
Also includes a coiled friction spring 70 with a continuous coil disposed between piston 30 and nut 54. As clearly shown in FIG. 1, the friction spring 70 is wound over the cylindrical portion of the nut 54 and has a bent end 72 fitted into a corresponding hole in the piston 30. End 72 of spring 70
is fixed to the piston 30, and the piston 30 is prevented from rotating, for example by a stud projecting from the friction member 20 into a groove in the outer end of the piston 30.

The direction in which the friction spring 70 is wound is
4 is rotated on the threaded rod 56 in a direction corresponding to the elongation of the extensible member formed by these two elements, i.e. to the left in FIG. It is like preventing the wheel from rotating in the opposite direction.

In accordance with the present invention, automatic adjustment device 48 also includes an adjustment limiting device, generally designated 74, that limits rotation of nut 54 on threaded rod 56 to a predetermined angle during operation of fluid drive device 26.

In the illustrated embodiment, as shown in FIG. It extends into the opening 80 substantially parallel to the axis of the piston 30 to form a circumferential connection with play between the retainer 78 and the abutment washer 62 . Additionally, a wire spring 82 is disposed between the rod 76 and the abutment washer 62 such that the rod 76 engages one of the circumferential edges of the aperture 80 when the fluid drive device 26 is released. Push the rod and abutment washer toward the relative position of. Spring 82 is generally circular and has a central portion 84 that curves radially inwardly to engage nut 54 . Furthermore, one end 86 of the spring 82 is bent substantially parallel to the axis of the piston 30 and is fitted into a hole in the abutment washer 62 and fixed to the washer, and the other end 88 of the spring 82 is a loop that engages the rod 76. is formed.

The disc brake described above operates as follows.

When the fluid drive device 26 is activated, pressurized fluid from the vehicle's master cylinder flows into the variable volume chamber 34 and pushes the piston 30 to the left in FIG. to engage. The reaction force causes the caliper 10 to slide along the mounting pin 12, causing the friction member 18 to engage the friction surface 22 of the disc 16. When this piston moves,
Since the actuating member 38 is held in the rest position by the spring 50, relative movement occurs between the piston 30 and the actuating member 38. An operating gap (not shown) typically provided inside the automatic adjustment device (for example, between the abutment washer 62 and the thrust ball bearing 64)
Once absorbed, the abutment washer 62 presses the nut 54 to the left via the thrust ball bearing 64. As a result, the reversible rotation characteristics of the screw 58 and the friction spring 7
The direction in which the nut 54 is wound causes the nut 54 to move in the direction corresponding to the elongation of the extensible member formed by these two elements on the threaded rod 56, i.e. in the second direction.
Rotate clockwise as shown. The stroke of the piston 30 required to operate the brake is determined by the stroke of the threaded rod 56.
If the rotation of the nut 54 above is such that it corresponds to the rotation of the retainer 78 by an angle α or less, the adjustment of the brake is not limited. When the nut 54 rotates, the retainer 78 of the thrust ball bearing 64 engages the abutment washer 62 and the nut 54.
A bearing 6 that freely rolls on surfaces facing each other.
It rotates with the ball number 4. Therefore, the retainer 78
is rotated by an angle α with respect to the abutment washer 62, the nut 54 is also rotated by an angle α with respect to the retainer, that is, the nut 54 is rotated by an angle 2α with respect to the abutment washer 62. . In this way,
The nut 54 is rotated on the threaded rod 56 through an angle less than or equal to the angle 2α to tighten the nut 54.
and the extensible member formed by rod 56 to define a new rest position for piston 30. When the fluid pressure in variable volume chamber 34 is released, piston 30 returns to its new rest position defined by rotation of nut 54 on threaded rod 56 upon actuation of fluid drive 26. At the same time, the direction in which the friction spring 70 is wound is opposite to the direction in which the extensible member extends.
The spring 82 prevents the nut 5 from rotating.
4. Return rod 76 to the position shown in FIG. 2 without rotating it.

If actuation of the fluid drive 26 causes a movement of the piston 30 such that the rotation of the nut 54 corresponds to the rotation of the retainer 78 by an angle α, the rod 76 engages the end edge in the rest position. Since the nut 54 engages with the circumferential edge of the opening 80 on the opposite side, rotation of the thrust ball bearing retainer 78 with respect to the abutment washer 62 is stopped, and the nut 54 also resists the large thrust force from the piston 30. Since the nut is frictionally engaged with the ball of the bearing 64 which is stopped, the nut cannot slide on the ball and is prevented from rotating relative to the threaded rod 56. From this point on, piston 30 simply moves in unison with self-adjuster 48 and actuating member 38 while compressing spring 50. Therefore, the rotation of the nut 54 is limited to a value that corresponds to the rotation of the angle α of the retainer 78 of the thrust ball bearing 64. In this way, the maximum amount of adjustment allowed by the adjustment limiting device 74 incorporated into the automatic adjustment device 48 is limited to an appropriately set value selected depending on the particular characteristics of the brake. The risk of over-adjusting the brakes is completely eliminated. When the fluid pressure within the variable volume chamber 34 is released, a number of elements of the self-adjusting device 48
The rotation of the rod 76 relative to the abutment washer 62 is less than or equal to the angle α.

During actuation of the mechanical drive 28, which is normally connected to the handbrake control of the vehicle, the shaft 36 is rotated clockwise in FIG. The actuating member 38 is pushed to the left via the element 40. This movement of member 38 tends to rotate nut 54 on threaded rod 56 in a direction that increases the frictional force between nut 54 and friction spring 70. Friction spring 70 therefore prevents rotation of nut 54, which allows all linear movement from actuating member 38 to be directed to piston 3.
0. Therefore, the friction member 20 is brought into direct engagement with the friction surface 24 of the disk 16, and sliding of the caliper along the mounting pin 12 causes the friction member 1
8 is engaged with the friction surface 22 of the disc 16 to mechanically actuate the brake. Upon release of the brake, springs 50 and 52 push shaft 36 and actuating member 38 toward the rest position, so that many elements of the brake return to the positions they occupied prior to mechanical actuation of the brake.

The present invention relates to a self-adjusting device and is not limited to the above-described embodiment detailed by way of example, but is suitable for any device such as a drum brake or clutch in which it is necessary to automatically compensate for the wear of friction members. The same can be applied.

Furthermore, although the invention has been described in connection with a disc brake, the invention is not limited to disc brakes of the above type described in detail by way of example.
In other embodiments (not shown), the disc brake has only a fluid drive and the self-adjusting device is therefore located between the piston and the cylinder provided with a threaded rod similar to rod 56. be done.
In another embodiment, the disc brake has a fluid drive including two pistons arranged rearwardly opposite each other, and two friction members similar to members 18 and 20 are moved through a caliper or movable frame. It is adapted to engage the rotating disk by reaction force or directly. in this case,
The self-adjusting device is placed between two pistons, one of which is provided with a threaded rod similar to rod 56.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a disc brake equipped with a fluid and mechanical drive including an automatic adjustment device embodying the present invention, and FIG. 2 is an enlarged sectional view taken along line 2--2 of FIG. 10...Calipa, 16...Disk, 18,
20...Friction member, 26...Fluid drive device, 28
... mechanical drive device, 30 ... piston, 32 ...
... Cylinder, 34 ... Variable volume chamber, 36 ... Rotating shaft, 38 ... Actuation member, 40 ... Force transmission element, 4
8... Automatic adjustment device, 54, 56... Element, 58
... Screw, 60 ... Actuation device, 62 ... Contact washer, 64 ... Thrust ball bearing, 70 ... Coil friction spring, 74 ... Adjustment limiter, 76 ... Rod, 7
8... Cage, 80... Circumferential opening, 82...
Wire spring, 84... part.

Claims (1)

Claims: 1. Automatically increasing the distance between two relatively movable parts of a device comprising a friction member, forming an extensible member, one of which extends from the first of the device. a pair of relatively rotatable elements connected non-rotatably to the parts; and a pair of relatively rotatable elements connecting a second part of the apparatus to the other of the elements, the other element being connected to the second part of the apparatus in a manner such that the other element is not rotated relative to the part; an actuating device for rotating the extensible member in a direction corresponding to elongation; and a one-way connection between a second portion of the device and the other element to prevent rotation of the other element in the opposite direction. an automatic adjustment device comprising a device, wherein the actuating device 60 is a second
It includes at least one abutment member 62 connected to the part 30 and cooperating with said other element 54 via a thrust bearing 64 including a retainer 78, said elements 54, 56 being connected via a counter-rotatable screw 58. The other element 5 cooperates with each other for each operation of the device.
An adjustment limiting device 74 is disposed between the retainer 78 and the abutment member 62 and includes a circumferential connection with play between them. An automatic adjustment device characterized in that the play allowed by the connecting portion limits the predetermined angle. 2. A patent characterized in that at least one rod 76 is provided in the retainer and is received in a circumferential opening 80 of the abutment member to form the circumferential connection with the play. An automatic adjustment device according to claim 1. 3. An elastic device 82 is disposed between the retainer and the abutment member to push the retainer and the abutment member toward a predetermined relative position when the device is not activated. An automatic adjustment device according to claim 1 or 2. 4 the elastic device comprises a wire spring 82;
A first end 86 of the spring is connected to the abutment member and a second end 88 is connected to the rod so that the rod is connected to the circumferential edge of the opening when the device is not activated. The automatic adjustment device according to claim 3, wherein the automatic adjustment device is brought into contact with each other. 5. The spring is generally circular and has a portion 84 therebetween that curves radially inwardly to engage the other element of the extensible member. The automatic adjustment device according to item 4. 6. A first end of the spring is bent parallel to the axis of the extensible member and fitted into a hole in the abutment member, and a second end of the spring forms a loop that locks onto the rod. An automatic adjustment device according to claim 4 or 5, characterized in that: